Method of preparing lantern slides



United States Patent 2,978,374 METHOD 0F PREPARING LANTERN SLIDFS Martin D. Collins, Schenectady, N.Y., assignor to General Electric Company, a corporation of New York No Drawing. Filed Mar. 26, 1956, Ser. No. 573,640

'7 Claims. (Cl. 154-95) This invention relates to a process for transferring fixed positive photographic images, said images being made by a one-step photographic process wherein a fixed positive image is withdrawn from the camera a short time after the picture is taken; and to the products so produced. More particularly, this invention relates to a process of preparing lantern slides from fixed positive images made by a one-step photographic process which comprises (1) preparing a fixed positive image on a suitable backing, such as paper, by means of a one-step photographic process, for example, the Land camera process; (2) applying to the face of said fixed positive image a coating of a translucent material, such as plastic or wax, which upon the application of heat and pressure is capable of withdrawing the image from the paper to a blank lantern slide; (3) placing the coated face of said fixed positive image in contact with the blank lantern slide; (4) applying sutficient heat and pressure thereto to cause the fixed positive print to adhere to the blank" lantern slide; and (5) thereupon removing the backing to leave a fixed positive image on the lantern slide.

Heretcfore, there has been developed a one-step photographic process for obtaining a fixed positive image whereby one obtains a fixed positive image from the camera within a short time after the picture is taken,

e.g. the Land camera process.

In general, the element contained in the Land camera comprises (1) a translucent base, such as a cellulosic film; (2) a. photosensitive layer thereon, such as silver chloride; (3) a water permeable, white, opaque layer thereon, such as gelatin containing titanium dioxide; and (4) a photosensitive paper thereon adapted by means of ice . lantern slide by the process described in the first paragraph. The significance. of this discovery is that within a very short time after the picture is taken, for example, in about 5 minutes, the positive image is ready to be projected upon a screen. This result is unexpected since the fixed positive image produced by the one-step process cannot be transferred by this process without a material, such as a plastic or wax, being applied to the face of the image (as described-in step 2 of my process), nor can a fixed positive image produced by the usual multi-step process (wherein the, image is developed outside the camera) be transferred by my process even with the application of a plastic or wax to the face of the positive image.

Among the translucent materials capable of withdrawing the image from the paper to a blank lantern slide, upon application of heat and pressure, are those waxes and plastics which have been used to protect the finished positive print taken by the one-step process from those hazards encountered in storage and display, such as, dirt or dust, fingerprints, scratches, reaction of certain chemicals in the prints with chemicals present in air, and the like. Examples of these materials which are disclosed in Land Patents 2,692,675 and 2,719,791 as high molecular weight polymers capable of forming a continuous film which is difficulty permeable to water and vapor include polyvinyl interpolymers and copolymers,.such as polyvinyl acetate, polyacrylates, and polymethacrylates, butadiene-styrene copolymers, polyvinyl chloride, and various natural and synthetic waxes and resins. Examples of water soluble materials include polyvinyl alcohol, sodium carboxymethyl cellulose, hydroxymethyl cellulose, sodium salts of polymethyacrylic and polyacrylic acids, etc. These can be applied to the surface of the'prints from solutions, suspension, emulsions thereof by rubbing these materials over the face of the prints.

a photosensitive chemical, such as silver chloride, to

have produced on its surface a positive image. Between (3) and (4) is a rupturable container containing a liquid developer, a silver chloride solvent, an alkali, etc. The process of employing this element comprises (1) exposing (2) through (1) to produce a' latent image; (11) drawing the element through a pressure roller which ruptures the container and spreads the processing solution between (3) and (4). This develops the latent image and permeates the positive unexposed photosensitive layer which is then exposed to light passing through the negative to give a latent'positive image which image is developed. The silver chloride solvent contained therein dissolves the unused silver chloride from the positive image to produce a positive print.

Examples of apparatus and processes for producing the one-treatment fixed positive image within a short period of time after the picture is taken are found in US. Patents 2,543,181, 2,563,342, 2,565,376, 2,698,237, 2,698,245, 2,719,472, 2,722,871, other related patents, and in an article entitled, A New One-Step Photographic Process," Journal of the Optical Society of America 37,

By reference, these Land Patents 2,692,675 and 2,719,791 are incorporated into this specification. Thus, the material applied to the surface is not only a bonding means but also exhibits a stabilizing, protective eifect on the print.

The amount of heat and pressure used in the process will, of course, depend on the particular wax or plastic employed. However, with each plastic, there is a lower limit of heat and pressure below which no transfer or an imperfect transfer will take place. Thus, using polyvinyl acetate, I have found that at a temperature of to 200 C., no transfer takes place below 1000 pounds per square inch (p.s.i.). In carrying out my process, I have advantageously employed pressures rang-- ing from about 1000 to 4000 p.s.i or higher, but preferably 2500 to 3000 p.s.i.,-and temperatures of 125 to 200 C., but preferably to 180 C. Although higher temperatures can be used, too high a temperature has a deleterious effect on the gelatin and discolors the silver salts in the image. 7

In order that those skilled in the art may better understand how the present invention may be practiced, the following examples are given by way of illustration and not by way of limitation. All parts are by weight.

Example 1 The process of Example 1 was repeated except that the photographic accessory of the type described in US. Patent 2,692,675 was used to apply the solution disclosed in Example 1. I taken, the image was projected on the screen.

Example 3 A solution containing 20 parts of polyvinyl alcohol in 50 parts of water and 30 parts of methanol is prepared and applied in a similar manner to Example 1. The resulting slide, ready to be shown within minutes after the picture is taken, is projected on a screen.

In addition to the resins disclosed above, other resins, such as those disclosed in the specification, may also be used.

Example 4 Examples 1, 2 and 3 were repeated except that fixed positive photographic images produced by the usual multistep process (wherein'the image is developed outside the camera) were used. These images were not transferred by the process.

This process is particularly useful for scientists and lecturers who wish to present slides of their work as their work progresses. The advantages of placing the image on a paper backing before transference is that one can view the print more easily, preserve it as such, or transfer it to a lantern slide.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A process of preparing a glass lantern slide from a blank glass lantern slide and a fixed photographic positive image on a backing material made by a one-step photographic process which comprises: 1) applying to the face of said fixed photographic image a coating of a translucent, high molecular weight polymer which upon application of heat and pressure is capable of withdrawing the image from the backing material and adhering it to a glass lantern slide; (2) placing the coated face of said fixed positive image in contact with the blank lantern slide; (3) adhering said fixed positive image to the blank glass lantern slide under a pressure of 1,000 to 4,000 pounds per square inch at a temperature of 125 to 200 0.; and (4) thereupon removing the backing material from the fixed positive image on the lantern slide.

2. An article comprising (1) a glass lantern slide,

Within 5 minutes after the picture was .4 (2) an intermediate layer of high molecular weight polymer which has been fused at a temperature of to 200 C. under a pressure of 1,000 to 4,000 pounds per square inch to said lantern slide and to (3) an image bearing layer which has been removed from the backing material on which it was independently supported during the one-step photographic process used to produce the image in the image bearing layer, said composite of (1), (2) and (3) formnig a lantern slide having a positive image which is capable of being projected by transmitted light onto a light reflecting surface.

3. An article as in claim 2 wherein the intermediate layer (2) comprises polyvinyl acetate.

4. An article as in claim 2 wherein the intermediate layer (2) comprises polyvinyl alcohol.

5. The process of preparing a glass lantern slide from a blank glass lantern slide and a fixed photographic positive image on a backing material made by a one-step photographic process which comprises: (1) applying to the face of said fixed photographic image a coating of a translucent material selected from the group consisting of polyvinyl alcohol and polyvinyl acetate; (2) placing the coated face of said fixed positive image in contact with a blank lantern slide; (3) adhering said fixed positive image to the blank glass lantern slide under a pressure of 1,000 to 4,000 pounds per square inch and a temperature of 125 to 200 C.; and (4) thereupon removing the backing material from the fixed positive image on the lantern slide.

6. The process of claim 5 wherein the translucent material is polyvinyl acetate.

7. The process of claim 5 wherein the translucent material is polyvinyl alcohol.

References Cited in the file of this patent UNITED STATES PATENTS 467,090 Frank et a1. Ian. 12, 1892 1,567,310 Weeks Dec. 29, 1925 2,154,474 Scott Apr. 18, 1939 2,171,259 Scott Aug. 29, 1939 2,252,632 Jones Aug. 12, 1941 2,421,764 Swallow June 10, 1947 2,611,720 Van Dyck et a1 Sept. 23, 1952 2,612,450 Land Sept. 30, 1952 2,627,485 Smith Feb. 3, 1953 2,627,486 Smith Feb. 3, 1953 2,661,290 Rackett Dec. 1, 1953 2,662,822 Land Dec. 15, 1953 2,719,791 Land Oct. 4, 1955 2,733,180 Pinto Jan. 31, 1956 2,798,021 Land July 2, 1957 OTHER REFERENCES The Photographic Journal, One-Step Photography, E. H. Land, January 1950; pages 7-15. 

1. A PROCESS OF PREPARING A GLASS LATERN SLIDE FROM A BLANK GLASS LATERN SLIDE AND A FIXED PHOTOGRAPHIC POSITIVE IMAGE ON A BACKING MATERIAL MADE BY A ONE-STEP PHOTOGRAPHIC PROCESS WHICH COMPRISES: (1) APPLYING TO THE FACE OF SAID FIXED PHOTOGRAPHIC IMAGE A COATING OF A TRANSLUCENT, HIGH MOLECULAR WEIGHT POLYMER WHICH UPON APPLICATION OF HEAT AND PRESSURE IS CAPABLE OF WITHDRAWING THE IMAGE FROM THE BACKING MATERIAL AND ADHERING IT TO A GLASS LANTERN SLIDE; (2) PLACING THE COATED FACE OF SAID FIXED POSITIVE IMAGE IN CONTACT WITH THE BLANK LANTERN SLIDE, (3) ADHERING SAID FIXED IMAGE TO THE BLANK GLASS LANTERN SLIDE UNDER A PRESSURE OF 1,000 TO 4,000 POUNDS PER SQUARE INCH AT A TEMPERATURE OF 125* TO 200*C., AND (4) THEREUPON REMOVING THE BACKING MATERIAL FROM THE FIXED POSITIVE IMAGE ON THE LANTERN SLIDE. 